Allergies and asthma in the industrialized world have increased in prevalence and severity over recent years. Asthma is now, in fact, the most common chronic illness among children.
Much is known about the pathogenesis of allergies and asthma. Both are immune-based diseases. Both are associated with an imbalance in the relative levels of type-1 and type-2 cytokines in the body. It has been observed that individuals with allergies or asthma have a higher relative ratio of type 2 to type 1 cytokines. It is believed that this skewed ratio then contributes to the pathogenesis of allergies and asthma.
In general, cytokines are cell-produced regulatory proteins that influence, in paracrine or autocrine fashion, cell function. They are produced by immune cells and are therefore categorized by their inducible function and the cell types involved in the response.
Type 1 cytokines, for example, elicit or augment primarily cell-mediated immune responses against pathogens. Type 1 cytokines are involved in inflammatory responses, viral immunity, intracellular parasite immunity and allograft rejection. Type 1 cytokines include interleukin 2 (IL-2), interleukin 12 (IL-12), and interferon γ (IFNγ). Type 1 cytokines can suppress the production of type 2 cytokines.
Type 2 cytokines, by contrast, elicit or augment primarily antibody-mediated immune responses against pathogens. Type 2 cytokines are involved in humoral responses, helminth immunity, and allergic responses. Type 2 cytokines include interleukin 4 (IL-4), interleukin 5 (IL-5), interleukin 10 (IL-10), and interleukin 13 (IL-13). Type 2 cytokines can suppress the production of type 1 cytokines.
Given the association between cytokine imbalance in allergies and asthma, it is believed that therapies directed to the normalization of the ratio of type 1 to type 2 cytokine levels will help treat or even prevent such diseases. To that end, it has now been discovered herein that β-hydroxy-β-methylbutyrate (HMB) exposure (in vitro) increases the relative ratio of type-1 to type-2 cytokines in stimulated peripheral blood mononuclear cells (PBMC), thus providing a potential new therapy for treating individuals having or at risk for developing allergies and asthma.
As a commercially available ingredient, HMB is found in a variety of nutritional products. It is also a metabolite of the essential amino acid leucine and is therefore found naturally in the human body. HMB is also found in a variety of plants, including citrus fruits and alfalfa, as well as in catfish. It is also known and used for a variety of purposes, including to build or maintain muscle mass in appropriate individuals and to enhance overall immune function.
To date, however, there have been no reports on the effect of HMB in modulating type 1 and type 2 cytokine production nor any disclosure of the use of HMB to affect cytokine imbalance in treating conditions responsive thereto, including allergies and asthma.